Objectives

National Transmission Company South Africa (NTCSA) seeks to collect comprehensive market intelligence on grid-forming technologies, specifically when integrated with battery energy storage systems (BESS). The primary objective is to evaluate how these technologies can address grid stability challenges caused by the planned decommissioning of conventional coal generation and the rapid expansion of inverter-based renewable resources. NTCSA aims to establish a clear, industry-wide understanding of available capabilities, performance boundaries, and compliance standards to inform future network planning and procurement strategies.

Scope

The RFI encompasses a rigorous technical assessment of grid-forming BESS across multiple operational domains. Respondents must address capabilities including autonomous voltage and angle formation, system strength provision, inertial response, oscillation damping, black start restoration, islanded operation, voltage regulation, fault ride-through, and phase jump mitigation. The scope extends to commercial and lifecycle considerations, requiring suppliers to quantify performance impacts on battery longevity, specify necessary equipment oversizing, and disclose associated cost premiums. Additionally, respondents must provide validated simulation models and demonstrate readiness for collaborative validation testing with the system operator.

Technical Requirements

• Comprehensive responses to a structured questionnaire covering extensive technical queries regarding GFM BESS performance.
• Submission of field test results, prototype studies, and capability curves demonstrating operation under varying short-circuit ratios (SCR), state-of-charge levels, temperature, and altitude conditions.
• Documentation proving compliance with internationally recognized grid codes and standards (e.g., UK, AEMO, Nordic frameworks).
• Provision of editable electromagnetic transient (EMT) and RMS dynamic models compatible with standard simulation platforms.
• Willingness to supply controller modules for hardware-in-the-loop and software-in-the-loop validation.
• Detailed analysis of multi-unit interactions, coordination with grid-following inverters, and functional curtailment effects.
• Clear delineation of operational limits, response times, and state-of-charge exclusions for each ancillary service.

Skills Requirements

Successful respondents must possess advanced engineering expertise in power electronics, high-voltage transmission systems, and battery storage integration. Required competencies include proficiency in grid-forming control algorithms, electromagnetic transient and RMS system modeling, laboratory and field testing protocols, and adherence to international grid code compliance. Suppliers must also demonstrate a verifiable track record of delivering grid-scale GFM BESS solutions to utility operators, alongside project management capabilities to support collaborative validation programs.

Explanation of Technical Terms

• Grid-Forming (GFM): Inverter technology that autonomously establishes grid voltage and frequency references, enabling stable operation in weak or low-inertia networks without relying on an existing grid signal.
• System Strength: The capacity of the electrical network to maintain voltage stability during disturbances, typically quantified by the Short Circuit Ratio (SCR).
• Inertial Response: Rapid active power injection or absorption to counteract frequency deviations following generation loss or load changes.
• Black Start: The ability to energize and restore a completely de-energized power system using internal stored energy, without external grid assistance.
• Island Mode: Autonomous operation of a localized network section, decoupled from the main transmission system, while maintaining stable power quality.
• Fault Ride-Through (FRT): The capability to remain synchronized and operational during severe voltage sags or swells, preventing unnecessary disconnection.
• EMT/RMS Modeling: High-fidelity simulation methods; EMT captures microsecond-level switching transients, while RMS analyzes slower electromechanical system dynamics.